Road planing machines

ABSTRACT

The invention consists of apparatus for machining road surfaces of the kind comprising a body having road wheels and carrying a cutting drum mounted for rotation about an axis extending transversely of the direction of travel and movable into contact with a road surface to cut away a layer of the surface in which there is a first hydrostatic pump, connected to a hydrostatic motor for driving the drum in which there is a second hydrostatic pump connected to a hydrostatic motor for driving at least one of the road wheels and in which there is means to drive both of the pumps at constant speed, and both of the pumps have infinitely variable displacements, means being provided for varying the displacements of the pumps individually whereby any combination of drum and road wheel speeds may be provided.

United States Patent 1w:

Gowler 1 June 10, 1975 1 1 ROAD PLANING MACHINES John Edward (iowler,Rcdhill. England 1751 Inventor:

22 Filed: Dec. 14. 1973 1211 Appl. N81424J23 130] Foreign ApplicationPriority Data Dec. 22, 1972 United Kingdom 59513/72 [521 U.S. C1. t.299/1: 173/24; 299/39 [51 1 Int. Cl. .1 E2lc 47/00 [58l Field of Search299/39. 14, I; 404/95, 404/77; 60/492; 180/53 CD; 172/123. 3; 173/24 [56References Cited UNITED STATES PATENTS 2.273154 2/1942 Davis 464/95 X3,300,000 1/1967 Stoykc 60/492 X 3.414.327 12/1968 Austin i l t r t i 1t 4 299/39 X 3.617.091 11/1971 Mooney 299/39 1767262 10/1973 Pentith299/39 X Primary ExaminerErnest R. Purser Assistant E.tuminer-Wi1liam F.Pate. lll

Attorney, Agent. or Firm-Young & Thompson 157] ABSTRACT The inventionconsists of apparatus for machining road surfaces of the kind comprisinga body having road wheels and carrying a cutting drum mounted forrotation about an axis extending transversely of the direction of traveland movable into contact with a road surface to cut away a layer of thesurface in which there is a first hydrostatic pump, connected to ahydrostatic motor for driving the drum in which there is a secondhydrostatic pump connected to a hydrostatic motor for driving at leastone of the road wheels and in which there is means to drive both of thepumps at constant speed, and both of the pumps have infinitely variabledisplacements. means being provided for varying the displacements of thepumps individually whereby any combination of drum and road wheel speedsmay be provided.

10 Claims, 7 Drawing Figures PATENTEDJUH 10 1975 SHEET PATENTED JUN 1 0I975 SHEET ROM) PLANING MACHINES The invention relates to apparatu formachining road surfaces and prmides apparatus for machining roadsurfaces of the kind comprising a body having road wheels and carrying acutting drum mounted for rotation about an axis extending trans\ersel ofthe direction of travel and movable into contact with a road surface tocut away a layer ol'the surface in which there is a first hydrostaticpump. connected to a hydrostatic motor for driving the drum in whichthere is a second hydrostatic pump connected to a hydrostatic motor fordriving at least one of the road wheels and in which there is means todrive both of the pumps at constant speed, and both of the pumps haveinfinitely variable displacements. means being provided to vary thedisplacements of the pumps individually whereby any combination of drumand road wheel speeds may be provided.

Such a machine provides great advantages over the known machinesparticularly because the control over the operating speeds of the drainand the road wheels is so much greater than in machines havingconventional mechanical drives. It has been previously preferred todrive the drum by hydrostatic means but this arrangement does notprovide sufficient control over the power and speed of the machine.

It is preferred that there are valve means for connecting the pumps tothe motors in a road machining position wherein the first pump isconnected to the drum motor and the second pump is connected to the roadwheel motor and a transit position wherein the first pump is connectedto the road wheels.

It is necessary to provide a relatively large amount of power to drivethe drum and a relatively small amount of power to drive the road wheelsduring machining, while a relatively large amount of power has to besupplied to the road wheels during transit from one place to another. Anadvantage of the above arrangement is that there is considerablelessening in the size of the second pump as the first pump which may bemuch larger can be used to drive the road wheels during transit.

Preferably the pumps are swash plate pumps driven by a single enginearranged to be driven at constant speed and the speeds at which themotors are driven is variable by varying the angle of the swash plates.

The hydrostatic motor for the drum may be mounted at least partly withinthe drum.

Preferably the drum is arranged to be driven by two hydrostatic motorsof which the rotors are arranged for rotation about the same axis. thedrum being mounted on the two rotors.

In a preferred arrangement there is at least one jockey wheel to controlthe depth of cut of the drum and there is at least one double actinghydraulic ram to control the position of the jockey wheel and pump meansto operate the ram. there being in the hydraulic connection between thepump means and the ram a hydraulic accumulator to absorb shock loads onthe jockey wheel.

There may be means to detect the position of the jockey wheel and meansto operate the ram in a sense to move the jockey n heel back to apredetermined position if the detection means detects movement of theheel from the said predetermined position.

Preferably the detection means comprises micro switches settable in aposition corresponding to a desired cutting depth.

The invention further provides a method of machining a road surfaceusing a machine of the kind comprising a body having road wheels andcarrying a cutting assembly having a cutting drum pivoted for rotationabout an axis extending transversely of the direction of travel whichcutting assembly has means to engage the road surface to limit the depthof cut of the drum in which during cutting the assembly is freelysuspended from the machine and the cutting pressure is provided solelyby the weight of the cutting assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevation of anapparatus according to this invention;

FIG. 2 is a schematic plan view of parts of the apparatus;

FIG. 3 is a view partly in section showing the arrangement andconstruction of the cutting drum. the ram being omitted for clarity.

FIG. 4 is an enlarged side elevation of the cutting drum and itsassociated parts;

FIG. 5 is a section through one rear road wheel showing the drivingmotor;

FIG. 6 is a diagrammatic drawing of the hydrostatic circuit; and

FIG. 7 is a diagrammatic drawing of the hydraulic circuit for thehydraulic rams for the depth controlling means.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION Referring firstto FIGS. 1 and 2 the apparatus comprises a chassis frame It), generallyof rolled steel section members suitably reinforced where necessary. Thechassis has mounted thereon two rear road wheels II, l2 two singlesteerable front road wheels 13, 14, an operators cab 15, a diesel engine16, a burner assembly 18, and a rotatable cutting drum 1'). The twofront wheels l3, l4 are steerable from the cab 15 via a mechanism (notshown). If desired window blades may be provided to keep cut materialaway from the path of the rear wheels.

Each rear wheel is driven by a single hydrostatic motor 21. FIG. 5 showsthe wheel I2 and the associated motor 21 which is secured to the chassisby a plate and is partially housed within the wheel hub.

FIGS. 3 and 4 show the cutting drum and its associated mountingarrangement and one of its two driving motors 22. The other motor (notshown) is mounted inside the other end of the drum. Each motor 22 isbolted to an internal radial flange 23 on the drum. The motors areconnected to the chassis [0 by a pivoted cradle 40 (FIG. 3) whichpermits the inclination of the drum axis to be varied from thehorizontal for use when planing a eambered road surface. or when cuttingaway a layer of varying depth.

A beam SI is attached to the chassis l0 and two lugs 52., 53 areattached to the beam SI. A tube 40 is pivotally mounted to the lugs 52,53 by two further lugs 54, 55 for rotation about a fore and aft axis.Pivotally mounted at each end of the tube 40 for rotation about atransverse axis in a support member 42. The drum I9 is attached to themembers 42 by means of the hydrostatic motors 22, one within each end ofthe drum. The

member 42. together with the drum I9, may be raised and lowered by ahydraulic ram 43 pivotally connected to the chassis and to a bar 56extending between the members 42. Connected to the support members 42are further legs 57, each carrying a roller which is inside the width ofthe cutting drum. The rollers 45 are adjustable in height relative tothe drum by means of hydraulic rams within the legs 57.

One cutting tooth 24 is shown welded to the periphcry of the steel drum19. There are however a plurality of such teeth arranged across the fullwidth of the drum along a line which, in developed form. has the shapeof a chevron or V. so that a single rotation of the drum re moves alayer of road surface having the full width of the drum. The cuttingdrum of this example has a width of 7 feet 6 inches. The longitudinalaxis of the drum is at 90 to the longitudinal axis of the apparatus.

The height of the drum relative to a road surface is variable byadjustment of the two wheels 45, and the drum may be lifted clear of theroad surface by means of ram 43.

Each cutting tooth 24 has an H cross-section and has a replaceablecarbide tip which can be reground, for example, as shown in U.S. Pat.No. 1,284,539.

The burner assembly I8 includes propane gas heaters 85 and is mounted infront of drum I9 and has the same width as the drum. The assembly hastwo mounting members 82a movable vertically in slides 82 and the heightof the assembly above the road is adjustable by means of a ram and twowires 83, 84 attached to the members 81. The assembly includes ahydraulically driven fan, ducting, controls. pipework and gauges. allnot shown.

FIG. 6 shows the main hydrostatic circuit for the machine. Swash-platepump 62 driven by engine 16 has a displacement variable by a lever 62a.The pump is connected to a reservoir 61. The drum motors 22 are con'nected to the pump circuit by means of valves 64 and 65 and areunidirectional. Each driven motor is provided with a cross line reliefvalve 66 to relieve pressure if shock loads are produced (e.g., when thedrum encounters a harder material) and the main feed lines are providednear the pump with cross line relief valves 63 which control thepressure of the circuit. The pump 62 and circuit may alternatively beconnected to the wheel drive motor 21 by way of valves 67, 81.

Swash plate pump 71 has a displacement variable by lever 71a and is fedfrom a reservoir 70. The pump 7] is less powerful than the pump 62.

The circuit for the pump 71 has two main lines lead ing to a valve 74having two positions. a first position where the lines are connected tothe supply and return lines to the motor 2l and a second position wherethe two main lines are connected together and the pump 7] is idling.

The main lines are interconnected by cross line relief valves 72 toregulate the pressure in the lines.

From the valve 74 the main line connects to the valve 75.

The motors 21 each have three connecting points A. B and C. In oneposition of the valve 75 fluid flows into the point A and out of thepoints B and C. This provides for half displacement ofthe motors givinglow torque/- high speed operating condition.

In a second position of the valve 75 fluid is caused to flow into thepoints A and B and out of point C. This provides for full displacementof the motors giving high torque/low speed operating condition.

Fail safe brake cylinders 77 are provided for the rear wheels I] and I2and the brakes are released as pressure builds up in the inlet linesleading to the points A or A and B.

A valve 78 is provided to connect together the input and output lines tothe motors 21 to allow the vehicle to be towed in the event of abreakdown.

The valves 64, 65. 67. 8] and 74 are all controlled simultaneously by aram 68 controlled by a valve 69 and supplied by a hydraulic pump 80. Thevalves move between a planing condition of the machine when the valves64. 65 connect the drum motors 22 into the circuit of the pump 62. thevalves 67. 81 are closed and the valve 74 is in its first positionconnecting the wheel motors 21 with the circuit of the pump 71'. and atransit position where the valves 67, 81 connect the wheel mo tors 21into the circuit of the larger pump 62, the valves 64, 65 are closed andthe valve 74 is in its second position allowing the pump 7] to freewheel.

The direction of rotation of the road wheels can be reversed byreversing the swash plate angle on the pump which is at that timeconnected to the road wheel motors 21. The speed of rotation of the drumand of the road wheels is similarly varied by varying the swash plateangles in the pumps while maintaining constant the speed of the engine16. The hydraulic circuit to the various rams is quite conventional. Theonly part ofthe circuit which needs explanation is shown in FIG. 7 whichshows the circuit to the rams controlling the roller height controlwheels 45.

A pump 9l fed from a reservoir 92 is connected to two solenoid operatedreversing valves 93 and hence to the two double acting rams 90. Thereversing valves are also connected to the reservoir 92. Each valve iscontrolled by two solenoids 95, 96 and the solenoids are controlledautomatically from microswitches attached to the wheel mountings. themicroswitches being settable in a position corresponding to a requireddepth of cut. Thus the height of the wheel 45 is adjusted automaticallyafter an initial setting and the depth of cut is kept constant even if,for example. fluid were to leak past the pistons of the rams 90 duringprolonged use.

Hydraulic accumulators 97 are provided in the circuits leading to thevertically uppermost sides of the rams 90 to cushion any shock loadsapplied to the wheels 45.

To carry out a machining operation the wheels 45 are adjusted in heightautomatically by the circuit of FIG. 7. If a different depth of cut fromthat set by the micro switches is required the electrical circuit to thesolenoids can be overriden from the cab. For example. if the cut is tobe deeper at one side that at the other then the wheel 45 at that oneside is set higher relative to the drum. Ram 43 is then completelyreleased allowing the drum to move into contact with the road surfaceunder its own weight and the apparatus is driven slowly along thesurface of a road in a forward direction with the ram 68 (FIG. 6)maintaining the hydrostatic circuit in the planing condition. The burnerassembly 18 heats and softens the road surface and drum I9 is driven inthe opposite direction to that of the road wheels to cut away a layer ofroad surface. If the road surface is cambered the wheels 45automatically angle the drum. tube 40 pivoting about the chassis.

When it is desired to transfer the machine from site to site the ram 68is used to move the hydrostatic cir can to the transit k'tll'ttllllttll.

The invention is not restricted to the details of the foregoing example.For instance the 7 feet 6 inches wide drum l9 and burner assembly 18 maybe replaced hy wider devices. Where the width of the de\iees exceeds theoverall width of the apparatus the burner assembly and drum may bemounted on one or more turntable devices so that for mmement of theapparatus from site to site the devices may he rotated in a hor izontalplane to swing the protruding ends of the devices inwardly so that theylie within the overall width of the apparatus.

lhere may two or more chevrons or \"s of teeth spaced circumferentiallyabout the cutting drum.

One important advantage of the machine just described is that thehydrostatic drive to the drum and the road wheels gives an infinitelyvariable speed range to the drive and the road wheels. This feature isnot available with conventional mechanical devices.

I claim:

1. Apparatus for machining road surfaces of the kind comprising a bodyhaving road wheels and carrying a cutting drum mounted for rotationabout an axis extending transversely of the direction of travel andmovable into contact with a road surface to cut away a layer of thesurface in which there is a first hydrostatic pump connected to ahydrostatic motor for driving the drum in which there is a secondhydrostatic pump connected to a hydrostatic motor for driving at leastone of the road wheels and in which there is means to drive both of thepumps at constant speedand both of the pumps have infinitely variabledisplacements, means being provided for varying the displacements of thepumps individually whereby any combination of drum and road wheel speedsmay be provided. and valve means for connecting the pumps to the motorsin a road machining position wherein the first pump is connected to thedrum motor and the second pump is connected to 6 the road wheel motorand a transit position wherein the first pump is connected to the roadwheels 2. Apparatus as claimed in claim I in which the pumps are swashplate pumps driven by a single engine arranged to be driven at constantspeed and the speed at which the motors are driven is variable byvarying the angle of the swash plates.

3. Apparatus as claimed in claim 1 in which a hydrostatic motor for thedrum is mounted at least partly within the drum.

4. Apparatus as claimed in claim 3 in which the drum is arranged to bedriven by two hydrostatic motors of which the rotors are arranged forrotation about the same axis the drum being mounted on the two rotors.

5. Apparatus as claimed in claim 1 in which the drum is arranged to bedriven in a direction of rotation opposed to that of the road wheels.

6. Apparatus as claimed in claim 5 including means for heating the roadsurface in advance of the drumv 7. Apparatus as claimed in claim 1including means to split the flow of fluid to the wheel motor to alterthe speed of rotation of the wheel motor.

8. Apparatus as claimed in claim 1 including at least one jockey wheelto control the depth of cut of the drum in which there is at least onedouble acting hydraulic ram to control the position of the jockey wheeland pump means to operate the ram there being in the hydraulicconnection between the pump means and the ram a hydraulic accumulator toabsorb shock loads on the jockey wheel.

9. Apparatus as claimed in claim 8 in which there is means to detect theposition of the jockey wheel and means to operate the ram in a sense tomove the jockey wheel back to a predetermined position if the detectionmeans detects movement of the wheel from the said predeterminedposition.

10. Apparatus as claimed in claim 9 in which the detection meanscomprises microswitches settable in a position corresponding to adesired cutting depth.

1. Apparatus for machining road surfaces of the kind comprising a bodyhaving road wheels and carrying a cutting drum mounted for rotationabout an axis extending transversely of the direction of travel andmovable into contact with a road surface to cut away a layer of thesurface in which there is a first hydrostatic pump, connected to ahydrostatic motor For driving the drum in which there is a secondhydrostatic pump connected to a hydrostatic motor for driving at leastone of the road wheels and in which there is means to drive both of thepumps at constant speed, and both of the pumps have infinitely variabledisplacements, means being provided for varying the displacements of thepumps individually whereby any combination of drum and road wheel speedsmay be provided, and valve means for connecting the pumps to the motorsin a road machining position wherein the first pump is connected to thedrum motor and the second pump is connected to the road wheel motor anda transit position wherein the first pump is connected to the roadwheels.
 2. Apparatus as claimed in claim 1 in which the pumps are swashplate pumps driven by a single engine arranged to be driven at constantspeed and the speed at which the motors are driven is variable byvarying the angle of the swash plates.
 3. Apparatus as claimed in claim1 in which a hydrostatic motor for the drum is mounted at least partlywithin the drum.
 4. Apparatus as claimed in claim 3 in which the drum isarranged to be driven by two hydrostatic motors of which the rotors arearranged for rotation about the same axis, the drum being mounted on thetwo rotors.
 5. Apparatus as claimed in claim 1 in which the drum isarranged to be driven in a direction of rotation opposed to that of theroad wheels.
 6. Apparatus as claimed in claim 5 including means forheating the road surface in advance of the drum.
 7. Apparatus as claimedin claim 1 including means to split the flow of fluid to the wheel motorto alter the speed of rotation of the wheel motor.
 8. Apparatus asclaimed in claim 1 including at least one jockey wheel to control thedepth of cut of the drum in which there is at least one double actinghydraulic ram to control the position of the jockey wheel and pump meansto operate the ram, there being in the hydraulic connection between thepump means and the ram a hydraulic accumulator to absorb shock loads onthe jockey wheel.
 9. Apparatus as claimed in claim 8 in which there ismeans to detect the position of the jockey wheel and means to operatethe ram in a sense to move the jockey wheel back to a predeterminedposition if the detection means detects movement of the wheel from thesaid predetermined position.
 10. Apparatus as claimed in claim 9 inwhich the detection means comprises microswitches settable in a positioncorresponding to a desired cutting depth.